If you used Block Images from... you used Firefox's internal image blocker, not Adblock. This feature is handled from Tools > Options > Web Features*. Click the Exceptions button next to the Load Images check box.

While you are there, make sure you have Load Images enabled, but for the originating web site only disabled. (Unless you really know what you are doing.)

If you are sure you used Adblock to block the images it is easy to see which filter is responsible. First, click the Adblock link on the status bar. Blocked images appear in red, and selecting them will show the offending filter below the list. You can remove or edit the filters in Tools > Adblock > Preferences._________________Adblock 0.5.3.042
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